Question: Complete the square to solve for $x$. $x^{2}+2x-8 = 0$
Begin by moving the constant term to the right side of the equation. $x^2 + 2x = 8$ We complete the square by taking half of the coefficient of our $x$ term, squaring it, and adding it to both sides of the equation. Since the coefficient of our $x$ term is $2$ , half of it would be $1$ , and squaring it gives us ${1}$ $x^2 + 2x { + 1} = 8 { + 1}$ We can now rewrite the left side of the equation as a squared term. $( x + 1 )^2 = 9$ Take the square root of both sides. $x + 1 = \pm3$ Isolate $x$ to find the solution(s). $x = -1\pm3$ So the solutions are: $x = 2 \text{ or } x = -4$ We already found the completed square: $( x + 1 )^2 = 9$